The invention relates to environmental control systems. More specifically, the invention relates to water removal apparatus for an aircraft environmental control system ("ECS").
Most aircraft air environmental control systems operate on an air cycle refrigeration principle. Compressed air is obtained from a source (such as a compressor section of an aircraft main engine), cooled with ambient air to near-ambient temperature in an air-to-air heat exchanger and then expanded in an air cycle machine to provide a stream of cooled, conditioned air. Water entrained in the air is typically removed by a water extractor. Cooled, conditioned air leaving the environmental control system is supplied to a passenger cabin. Although somewhat expanded, the conditioned air also pressurizes the cabin.
A high pressure water extractor typically removes the entrained water prior to expansion in the air cycle machine, whereas a low pressure water extractor typically removes the entrained water following expansion in the air cycle machine. If the air cycle machine has two cooling stages (i.e., a high pressure stage and a low pressure stage), mid-pressure water separation may be performed on air expanded by the high pressure stage, but prior to expansion in the low pressure stage.
There is an ongoing need to reduce the weight of an aircraft. Reducing the aircraft weight would reduce in-flight fuel consumption which, in turn, would reduce operating costs. Therefore, it would be desirable to reduce the weight of the water extractor to help meet this need.
It would also be desirable to reduce the size (primarily length) of the water extractor. Reducing the size of the water extractor would reduce the size of the environmental control system and thereby make the environmental control system easier to fit in the aircraft. The available envelope for the environmental control system is usually quite small.
It would also be desirable for a lower pressure drop across the water extractor. A lower pressure drop would allow for greater ECS capacity given the same engine performance, or it would reduce engine fuel consumption given the same ECS capacity.